This invention relates in general to timing devices and in particular to a timing device for controlling the operation of a printing machine.
Hitherto a number of decentralized timing devices have been used in connection with printing machines to control a particular partial operation such as for example a clocked sheet control, the correct sequence of feeding and discharging of prints, to synchronize sorting of sheets and the like.
From the German Pat. No. 2,220,601 a control system for multicolor rotary printing machines is known which controls the operation of printing units of the machine or individual functional groups in respective printing units in order to pass a sheet through the machine at a correct sequence of time points. This known control system includes a pulse generating stage consisting of a signal generator, an interrogating device, a signal shaper and a closed chain of shift registers to produce a timing signal corresponding to an integer part of a rotation of the cycle shaft of the machine relative to a preset angular position of the latter.
The disadvantage of this prior art timing pulse generating stage is the fact that it is designed for a single application only and consequently there are necessary many control units in the printing machine to control a variety of functions.
Furthermore, it is also disadvantageous that this known pulse generating stage can deliver only non-modified timing signals and is not designed for ready modification of its output, for example for delivering timing signals dependent on rotary speed of the machine as it is frequently desirable for controlling idling times of adjustment elements of the printing machine.
Furthermore, in order to produce timing pulses of different length the prior art control system necessitates the use of pulse shapers which again are suitable for producing a non-variable impulse length only.